Archived Sb 3.1 – Xanthomonas axonopodis pv glycines – soybean
| Version | - |
|---|---|
| Date | - |
| Pathogen | Xanthomonas axonopodis pv. glycines (syn: Xanthomonas campestris pv. glycines) |
| Host | Soybean (Glycine max) |
| Common Name | bacterial pustule |
| Method | Sb 3.1 MXG selective media (Prathuangwong et al., 1997) |
| Method Class | Temporary Standard (B) |
| Sample | 5000 seeds |
Procedure:
- Seeds are surfaced sterilized with 95% ethyl alcohol for 30 sec.
- Seeds are plated on MXG selective medium amended with 1 ml of a 50 mg/ml stock solution of polymixin B sulfate/ liter.
- Plates are incubated at room temperature for 2 weeks.
- Presumptive colonies of X. campestris pv glycines are distinguished by morphological characteristics including color and size.
Biochemical tests:
- Subcultures on plates of nutrient glucose agar are identified by a range of biochemical tests including oxidase reaction, acid and gas production from carbon sources, gram staining, and production of indoleacetic acid.
Pathogencity test:
- Cultures are grown on nutrient glucose broth overnight and adjusted to a concentration of 107 cfu/ml.
- Leaves of a 3-5 day old soybean plant (cultivar SJ14 or other susceptible variety) are inoculated.
- Plants are evaluated for symptom development after 7-10 days at 30-34oC and 79-95% relative humidity.
Recipes:
MXG:
Prepared MXP agar:
| Reagent | Quantity |
|---|---|
| Distilled Water | 1000 mL |
| K2HPO4 | 0.8 g |
| KH2HPO4 | 0.6 g |
| Yeast Extract | 0.7 g |
| Soluble Starch | 0.8 g |
| Glucose | 1.0 g |
| Agar | 15.0 g |
Additional ingredients:
1 ml methyl green (1% in 20% ETOH)=1 ml per liter of MXP, pH = 7.2-7.4 and autoclaved.
After cooling add filter sterilized:
| Reagent | Quantity |
|---|---|
| Cycloheximide (50 mg/ml in 12.5% methanol) | 1 mL |
| Cephalexin (50 mg/ml aqueous) | 1 mL |
| Bacitran (10 mg/ml aqueous) | 1 mL |
| Kasugamycin (50 mg/ml aqueous) | 1 mL |
References:
Prathuangwong, S., Khandej, K., and Goto, M. 1997. Development of new methods for ecological study of soybean bacterial pustule: A semiselective medium for detecting Xanthomonas campestris pv. glycines in contaminated soybean seed. pp 197-202 in: Banpot Napompeth (ed). Proceedings of World Soybean Research Conf. V, Chiangma, Thailand 1994.